A method for fixing chromated copper arsenate agents in wood by treating the wood with a fixing agent selected from the following: ##STR1## wherein R1 is the same or different and is hydrogen, phenyl or an alkyl group having 1 to 4 carbon atoms, R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms and R3 is (R4)2 (HO)C-- or R4 OOC-- and R4 is hydrogen, an alkyl group having 1 to 4 carbon atoms, phenyl or pyridyl.
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1. A method for fixing chromated copper arsenate agents in wood comprising the steps of impregnating the wood with chromated copper arsenate; and treating the chromated copper arsenate impregnated wood with a fixative agent selected from the group consisting of compounds having the formula ##STR4## and salts thereof, wherein R1 is the same or different and is selected from the group consisting of hydrogen, phenyl or an alkyl group having 1 to about 4 carbon atoms, R2 is selected from the group consisting of hydrogen and an alkyl group having from 1 to about 4 carbon atoms and R3 selected from the group consisting of (R4)2 (HO)C-- and R4 OOC-- wherein R4 is selected from the group consisting of hydrogen, an alkyl group having 1 to about 4 carbon atoms, phenyl and pyridyl.
9. A method for fixing chromated copper arsenate agents in wood comprising the steps of impregnating the wood with chromated copper arsenate; treating the chromated copper arsenate impregnated wood with a fixative agent selected from the group consisting of compounds having the formula ##STR6## and salts thereof, wherein R1 is the same or different and is selected from the group consisting of hydrogen, phenyl or an alkyl group having 1 to about 4 carbon atoms, R2 is selected from the group consisting of hydrogen and an alkyl group having from 1 to about 4 carbon atoms and R3 is selected from the group consisting of (R4)2 (HO)C-- and R4 OOC-- wherein R4 is selected from the group consisting of hydrogen, an alkyl group having 1 to about 4 carbon atoms, phenyl and pyridyl; and employing mandelic acid as said fixative agent in treating the chromated copper arsenate impregnated wood.
7. A method for fixing chromated copper arsenate agents in wood comprising the steps of impregnating the wood with chromated copper arsenate; treating the chromated copper arsenate impregnated wood with a fixative agent selected from the group consisting of compounds having the formula ##STR5## and salts thereof, wherein R1 is the same or different and is selected from the group consisting of hydrogen, phenyl or an alkyl group having 1 to about 4 carbon atoms, R2 is selected from the group consisting of hydrogen and an alkyl group having from 1 to about 4 carbon atoms and R3 is selected from the group consisting of (R4)2 (HO)C-- and R4 OOC-- wherein R4 is selected from the group consisting of hydrogen, an alkyl group having 1 to about 4 carbon atoms, phenyl and pyridyl; and employing picolinic acid as said fixative agent in treating the chromated copper arsenate impregnated wood.
12. A method for fixing chromated copper arsenate agents in wood comprising the steps of impregnating the wood with chromated copper arsenate; treating the chromated copper arsenate impregnated wood with a fixative agent selected from the group consisting of compounds having the formula ##STR7## and salts thereof, wherein R1 is the same or different and is selected from the group consisting of hydrogen, phenyl or an alkyl group having 1 to about 4 carbon atoms, R2 is selected from the group consisting of hydrogen and an alkyl group having from 1 to about 4 carbon atoms and R3 is selected from the group consisting of (R4)2 (HO)C-- and R4 OOC-- wherein R4 is selected from the group consisting of hydrogen, an alkyl group having 1 to about 4 carbon atoms, phenyl and pyridyl, and wherein the fixative agent is contained in an aqueous solution; and treating the wood by a modified full cell treating cycle with the aqueous solution containing the fixative agent after the wood has been treated with the chromated copper arsenate agent.
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1. Field of the Invention
The present invention relates to the preservation of wood and, in particular, the preservation of wood by means of chromated copper arsenate solutions.
2. Brief Description of the Prior Art
The preservation of wood under pressure with various chromated copper arsenate (CCA) solutions is well known in the art. Such solutions are described, for example, in the American Wood Preservers' Association Book of Standards (1987), Section P5-86, pages 2 and 3.
Fixation is a process whereby CCA solutions undergo reaction with wood to be relatively insoluble. The process involves the reaction of hexavalent chromium with wood to give trivalent chromium and a corresponding reduction in acidity, thereby producing insoluble CCA-wood compounds. The reaction of hexavalent chromium with wood is slow at ambient temperatures, typically requiring several days for completion. The reaction can be accelerated by heat. In order to enhance fixation of CCA-wood commercially, a variety of heating techniques have been developed which include kiln drying, steam treatment, and microwave treatment. A disadvantage, however, of such techniques is that they require considerable capital investment and are time consuming. It is, therefore, the object of the present invention to provide a means for fixing aqueous CCA chemicals in wood both quickly and inexpensively.
A chemical treatment method has been discovered that rapidly fixes the CCA chemicals in wood. The method consists of treating the CCA impregnated wood with a second solution containing a suitable reducing agent in the treating cylinder, thus reducing capital expenditures. Suitable reducing agents for use in the method of the present invention include those having the following formulae: ##STR2## and salts thereof, wherein R1 is the same or different and is hydrogen, phenyl or an alkyl group having 1 to 4 carbon atoms; R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms and R3 is (R4)2 (HO)C-- or R4 OOC-- wherein R4 is hydrogen, an alkyl group having 1 to 4 carbon atoms.
Hydrazine is an example of the compounds having the first formula above. It is a commonly used reducing agent and anti-corrosion material. As a reducing agent, it is capable as follows of reaction on both acid and alkaline solutions:
N2 H5+ →N2 +5H+ +4e'
and
N2 H4 +4OH- →N2 +4H2 O+4e'
giving nitrogen as a by-product. The reaction of hydrazine with chromium (VI) is:
3N2 H5+ +4CrO42- +17H+ →3N2 +4Cr3+ +16H2 O
with the by-products being nitrogen and water.
Alpha-hydroxylamine and beta-hydroxylamine are, respectively, examples of the compounds having the second and third formula above. They are reducing agents and their reaction with chromium (VI) is:
6NH2 OH+2CrO42- +10H+ →3N2 +2Cr3+ +14H2 O
with the by-products of hydroxylamine being nitrogen and water.
Included in the compounds having the fourth formula, above, are a variety of materials which enhance chromium (VI) oxidation reactions. These materials are capable of forming mono- and di-esters with chromic acid. Amont these are oxalic acid, glycolic acid, picolinic acid, 2-hydroxy-2-methylbutyric acid, and mandelic acid. The mono-Cr(VI) esters are typified by five membered rings:
The present invention is further explained with reference to the accompanying drawings in which:
FIG. 1 is a graph of CCA fixation versus temperature for various temperatures in a full cell treating process;
FIG. 2 is a graph of CCA fixation versus temperature for two temperatures in a modified full cell treating process;
FIG. 3 is a graph of hydrazine penetration versus concentration and time at pressure for various concentrations of hydrazine; and
FIG. 4 is a graph of hydrazine retention and penetration versus pressure for one plant trial described herein.
While the preparation of CCA solution is well known, the preparation of one type (50% concentration, Type C) would be accomplished by first charging a stirred vessel with 39 parts water and then adding 28 parts of 75 percent H3 Aso4 (arsenic acid) solution. (As2 O5 is present as H3 AsO4). 23.75 parts CrO3 flake or crystal is then added and stirred until dissolved. 9.25 parts CuO powder is then added. The CuO is stirred until it is dissolved. The reaction with CuO is exothermic and the temperature should not exceed 180° F. The resulting solution is red-brown in color and has a density of 1.82 g/cc. It would be diluted with water to 0.5-4.0 percent concentration before use.
The wood is treated in a steel pressure cylinder, typically 6 ft. to 8 ft. in diameter and 60 ft. to 120 ft. long. The wood is loaded on wheeled trams, rolled into the cylinder and the cylinder closed and sealed. An initial vacuum is drawn on the cylinder to remove air from the wood cells, then the treating solution is admitted to the cylinder and pressure applied, typically 150 p.s.i.g. After a period of time, the cylinder is drained and a final vacuum pulled on the cylinder to remove excess solution that would otherwise ooze out slowly, causing the wood to drip. The final vacuum is typically about 26 inches of mercury. Two basic variations of treating cycle are currently in use, "full cell" and "modified full cell", distinguished by how much initial vacuum is used. Full cell cycles, so called because the wood cells are filled with solution, use a "full" vacuum of about 26 to 28 inches of mercury, whatever the equipment can reach. Modified full cell cycles use a partial initial vacuum, anywhere from 7 inches to 20 inches. Although it is not extensively used on an empty cell cycle procedure in which there is no initial vacuum and sometimes even a few p.s.i.g. of initial air pressure could also be employed. The amount of air in the wood cells when the solution is introduced will largely determine how much solution is retained by the wood and, hence, how long it will take to dry after treatment.
In the method for the present invention a cycle that permits impregnation of the wood with a second solution is desired. Typically, the wood is treated by the modified full cell cycle after which the second, fixative solution is introduced to the cylinder. A second modified full cell cycle is similarly used for this second treatment with the fixative agent. The fixative solution consists of about 0.5 to 4.0 weight percent by weight reagent. Normally about 1.0 to 2.0 percent is used for adequate CCA wood fixation.
To further explain the method and composition of the present invention and demonstrate its advantages over the prior art, the following examples and comparative tests are provided.
This test demonstrates results for thermal fixation in a full cell treating cycle. Thirteen 11/2" blocks of southern yellow pine were pressure treated with a 2.00 percent CCA oxides solution, made by diluting a 50 percent WOLMANAC® concentrate with de-ionized water. The treating cycle consisted of 10 minutes at vacuum, 24 inches of mercury, and 30 minutes at 150 p.s.i.g. pressure. The treating data are given in Table 1. Samples 1-3 were placed in a desiccator over water and maintained at 50°C Similarly, samples 4-6, 7-9 and 10-12 were maintained at 23°, 4° and 80°C, respectively. Sample 13 was squeezed immediately after CCA treatment using a hydraulic press to yield about half the total impregnated solution. The remaining blocks were removed at various time intervals and similarly squeezed. Chromium (VI) content was measured immediately by titration with standardized iron (II) solution. The percent fixation was calculated using the equation ##EQU1## The results of these experiments are summarized in Table 2 and graphically illustrated in FIG. 1 for full cell treating cycle.
This test demonstrates results for thermal fixation in a modified full cell treating cycle. Twelve 11/2", southern yellow pine blocks were treated with a 2.00 percent CCA oxide solution. The modified full cell cycle used consisted of two minutes initial vacuum (10 inches of mercury), thirty minutes at 120 p.s.i.g. pressure and thirty minutes at 25 inches of mercury final vacuum. The treating data are given in Table 3. Samples 1-6 were placed in a desiccator, over water to prevent drying, and maintained at 23°C Samples 7-12 were also placed in a desiccator as above, however, these samples were maintained at 80°C At various time intervals, samples were removed (two samples at 23°C and three at 80°C) and squeezed via a hydraulic press. These extrudates were immediately titrated with standardized iron (II) so as to determine the remaining, unreduced, soluble chromium (VI). The results of these experiments are summarized in Table 4 and illustrated in FIG. 2.
Two laboratory studies were performed using 0.5 and 1.0% aqueous hydrazine solutions, prepared by diluting 85% hydrazine hydrate, as the second solution for rapid fixation. The experimental technique involved the use of 1.5 inch southern yellow pine blocks and the "squeeze method". The treating cycle used a 2.0% CCA modified full cell to give nominal 0.4 pcf CCA oxides followed by hydrazine solution modified full cell. The treating cycle used is given in Table 5. The treating data for the 0.5 and 1.0% hydrazine treatments are given in Tables 6 and 7, respectively. Blocks from each treatment with CCA-C/hydrazine were "squeezed" via a hydraulic press to obtain solution for chromium (VI) analysis. No chromium (VI) could be detected. Thus, fixation was 99+ percent complete in this laboratory study.
Experiments were performed using end sealed (1.5×3.5×7.0 inch) samples which illustrated the impact of hydrazine concentration and time at a specific pressure (150 p.s.i.g.). These results are summarized in Table 8 and illustrated in FIG. 3.
A scale-up of the dual, modified full cell CCA-hydrazine treatment was done. A computerized 3'×12' treating cylinder was used for the scale-up activity. The system was placed in manual mode and the CCA and hydrazine solutions were piped directly into the bottom of the cylinder via quick-disconnect hoses. A 1.8% CCA-C solution was prepared from a commercial 50% concentrate. The 1.0% hydrazine was prepared from MOBAY® 85% hydrazine hydrate. The treatment of some nine cubic feet of southern yellow pine lumber stock is given in Table 9. Examination of cross-sections from this treatment of lumber showed hydrazine penetration or CCA fixation of approximately 0.25 inch. Drips from this charge of lumber and two others were collected and analyzed by atomic absorption spectroscopy. These analyses along with a typical analysis of a 1.8% CC-C solution are given in Table 10. The CCA content of these drips are two to three orders of magnitude less than the CCA treating solution and are approaching values that might be obtained by the EP Toxicity Test for CCA-C/southern yellow pine sawdust, i.e. 5-10 ppm for each element. A charge of pole stubs was similarly treated in the pilot plant cylinder. The treating data and cycles are given in Table 11. After treatment and drying, these stubs were cut in half to reveal the depth of hydrazine penetration and CCA fixation. For southern yellow pine, the hydrazine penetration ranged between 0.25 inches to total penetration of the sapwood. For the red pine and lodge pole pine, the hydrazine penetrations ranged between 0.25 to 0.75 inches.
A plant trial was conducted using a 1.8-1.9 percent CCA-C solution prepared by diluting WOLMAN® concentrate, and a 1.0% hydrazine solution, made by diluting MOBAY® 85 percent hydrazine hydrate. The wood was nominal two inches southern yellow pine lumber and is described in Table 12. The treating data for this trial are given in Table 13 for both the CCA and hydrazine cycles. Samples of lumber were obtained from each charge. Cross-sections indicate hydrazine penetration ranged from 1/32 to 3.8 inch depending on the applied pressure. The hydrazine penetration and CCA wood fixation was 3/8, 1/8, 1/16, and 1/32 inch for charges 1 to 4 respectively. These hydrazine solution retentions and depth of penetrations are plotted in FIG. 4.
This example demonstrates the use of hydroxylamine. A 2.00% CCA-C solution was prepared by diluting 153.6 g of 52.1% WOLMAN® concentrate with 3846 g water. The 2.00% hydroxylamine sulfate was prepared by dissolving 60.0 g hydroxylamine sulfate in 2940 water. A dual modified full cell cycle was used for treating 1.5 inch southern yellow pine blocks. The cycle and treating data are described in Table 14. The blocks were squeezed via a hydraulic press immediately after treatment. No chromium (VI) was detected in the extrudate. Thus fixation of CCA wood was 99+ percent complete.
This example demonstrates the use of oxalic acid. Twelve 1.5 inch blocks of southern yellow pine were treated in dual modified full cell treating cycles. The cycles used are described in Table 15. The treating data are reported in Table 16. These treated blocks were placed in a desiccator, above water to prevent drying at 23°C At various time intervals, these blocks were removed and "squeezed". The three extrudates were combined and the chromium (VI) was analyzed as above. The analyses are given in Table 17. Increasing the concentration of oxalic acid in subsequent experiments to 2.0 percent, gave 99+ percent fixation based on chromium (VI) in the extrudate within 0.10 day.
| TABLE 1 |
| ______________________________________ |
| Full Cell Treatment |
| 2.00% CCA-C |
| Treating Data |
| % Oxides |
| Sample |
| Pre Treat Post Treat |
| Soln. Gain |
| Soln. Retention |
| No. Wt. (g) Wt. (g) (g) Gain (pcf) |
| ______________________________________ |
| 1 31.09 73.55 42.46 136.57 |
| 0.93 |
| 2 28.54 71.28 42.74 149.75 |
| 0.93 |
| 3 28.80 71.47 42.67 148.16 |
| 0.93 |
| 4 30.91 72.54 41.63 134.68 |
| 0.91 |
| 5 31.12 72.16 41.04 131.88 |
| 0.90 |
| 6 33.44 74.49 41.05 122.76 |
| 0.90 |
| 7 29.75 74.01 44.26 148.77 |
| 0.97 |
| 8 29.91 72.30 42.39 141.73 |
| 0.93 |
| 9 32.62 74.40 41.78 128.08 |
| 0.91 |
| 10 40.33 73.97 33.64 83.41 |
| 0.73 |
| 11 39.13 74.70 35.57 90.90 |
| 0.77 |
| 12 35.39 72.52 37.13 104.92 |
| 0.81 |
| 13 28.31 (Squeezed immediately) |
| ______________________________________ |
| TABLE 2 |
| ______________________________________ |
| CCA Fixation versus Temperature |
| Determined from chromium(VI) measurement for a full cell |
| treating cycle treated to 0.9 lbs. CCA oxides per |
| cubic foot of southern yellow pine |
| Temp. Time Percent Time Percent |
| Time Percent |
| °C. |
| Days Fixation Days Fixation |
| Days Fixation |
| ______________________________________ |
| 4 1.1 60 10.9 83 30.1 91 |
| 23 1.1 72 1.9 88 10.9 99+ |
| 50 0.16 51 0.81 96 1.9 99+ |
| 80 0.07 72 0.14 94 0.17 |
| 99+ |
| ______________________________________ |
| TABLE 3 |
| ______________________________________ |
| Modified Full Cell Treatment |
| 2.00% CCA-C |
| Treating Data |
| % Oxides |
| Sample |
| Pre Treat Post Treat |
| Soln. Gain |
| Soln. Retention |
| No. Wt. (g) Wt. (g) (g) Gain (pcf) |
| ______________________________________ |
| 1 33.55 52.85 19.30 57.53 0.44 |
| 2 33.20 52.94 19.74 59.46 0.45 |
| 3 36.12 54.50 18.38 50.89 0.41 |
| 4 30.47 50.36 19.89 65.28 0.45 |
| 5 36.06 56.11 20.05 55.60 0.45 |
| 6 31.60 54.25 22.65 71.68 0.51 |
| 7 42.53 60.58 18.05 42.44 0.32 |
| 8 41.85 59.48 17.63 42.13 0.32 |
| 9 34.15 50.13 15.98 46.79 0.36 |
| 10 33.04 48.89 15.85 47.97 0.37 |
| 11 40.13 59.02 18.89 47.07 0.36 |
| 12 35.49 59.91 24.42 68.81 0.53 |
| ______________________________________ |
| TABLE 4 |
| ______________________________________ |
| CCA Fixation versus Temperature |
| Determined from chromium(VI) measurement for a modified |
| full cell treating cycle treated to 0.4 lbs. CCA oxides per |
| cubic foot of southern yellow pine |
| Temp. Time Percent Time Percent |
| Time Percent |
| °C. |
| Days Fixation Days Fixation |
| Days Fixation |
| ______________________________________ |
| 23 0.16 56 1.1 86 2.2 97 |
| 80 0.10 93 -- -- -- -- |
| 0.16 99+ |
| ______________________________________ |
| TABLE 5 |
| ______________________________________ |
| Treating Cycle for Dual Modified Full |
| Cell Chemical Fixation |
| CCA-C Hydrazine |
| First Cycle |
| Second Cycle |
| ______________________________________ |
| Initial Vacuum, inches Hg |
| 10 10 |
| Pressure, psig 150 150 |
| Pressure, minutes 30 30 |
| Final Vacuum, inches Hg |
| 27 27 |
| Final Vacuum, minutes |
| 30 30 |
| ______________________________________ |
| TABLE 6 |
| ______________________________________ |
| Treating Data |
| Chemical Fixation: Dual Modified Full Cell Treatment |
| 2.00% CCA-C/0.5% Hydrazine |
| Pre Treat Post Treat Soln. Gain |
| % Soln. |
| Wt. (g) Wt. (g) (g) Gain |
| ______________________________________ |
| 43.88 61.30 17.42 39.70 |
| 29.04 47.27 18.23 62.78 |
| 41.80 59.16 17.36 41.53 |
| ______________________________________ |
| TABLE 7 |
| ______________________________________ |
| Treating Data |
| Chemical Fixation: Dual Modified Full Cell Treatment |
| 2.00% CCA-C/1.0% Hydrazine |
| Pre Treat Post Treat Soln. Gain |
| % Soln. |
| Wt. (g) Wt. (g) (g) Gain |
| ______________________________________ |
| 38.48 55.15 16.67 43.31 |
| 42.88 60.60 17.72 41.32 |
| 38.94 56.77 17.83 45.79 |
| 34.67 49.03 14.36 41.42 |
| 28.68 44.89 16.21 56.52 |
| 35.75 50.49 14.74 41.23 |
| ______________________________________ |
| TABLE 8 |
| ______________________________________ |
| Hydrazine Penetration vs Hydrazine |
| Concentration and Time at Pressure |
| Depth of Penetration, inches |
| Hydrazine, % 15 min. 30 min. |
| ______________________________________ |
| 0.5 0.25 0.34 |
| 2.0 0.38 -- |
| 4.0 0.50 0.75 |
| ______________________________________ |
| TABLE 10 |
| ______________________________________ |
| Analysis of Drips from Hydrazine Fixed |
| CCA-C Treated Lumber |
| Element Drips (ppm) |
| 1.8% CCA-C |
| ______________________________________ |
| Cr 5-17 4400 |
| Cu 5-14 2700 |
| As 20-45 4000 |
| ______________________________________ |
| TABLE 11 |
| __________________________________________________________________________ |
| CCA - Hydrazine |
| Pilot Plant Study #4 |
| __________________________________________________________________________ |
| Treatment #5 |
| 1st Soln. |
| 2nd Soln. |
| 2nd Soln. |
| Sample |
| Sample |
| Sample Pre Treat |
| Post Treat |
| Retention |
| No. Species |
| Size Wt. (lbs.) |
| Wt. (lbs.) |
| pcf |
| __________________________________________________________________________ |
| P-1 Red Pine |
| 2.08 × 10.92 |
| 120.5 160.5 10.64 |
| P-2 SYP 2.54 × 12.08 |
| 274.5 306 5.62 |
| P-3 Lodge Pole |
| 1.98 × 10.75 |
| 116.0 155 11.45 |
| P-4 SYP 2.13 × 10.25 |
| 153.0 218 16.49 |
| L-1 SYP 1.5 × 5.5 × 12.0 |
| 21.82 |
| 35.52 |
| 23.91 |
| __________________________________________________________________________ |
| Treating Cycle |
| 1.8% CCA |
| Initial Vacuum/Fill (7" Hg) |
| 10 min. |
| Pressure (120 psig) 33 min. |
| Pressure Release 7 min. |
| Blow Back (15 psig) 7 min. |
| Final Vacuum (27" Hg) 39 min. |
| 1.0% Hydrazine |
| Initial Vacuum (27" Hg) |
| 12 min. |
| Fill (27" Hg) 6 min. |
| Pressure (150 psig) 30 min. |
| Pressure Release 5 min. |
| Blow Back (15 psig) 8 min. |
| Final Vacuum (25" Hg) 60 min. |
| __________________________________________________________________________ |
| TABLE 12 |
| ______________________________________ |
| Plant Trial Chemical Fixation |
| Charge Descriptions |
| Charge No. Pieces |
| Charge Description |
| ______________________________________ |
| 1 132 2" × 8" × 16' |
| 1500 2" × 8" × 6' |
| 2 132 2" × 8" × 16' |
| 432 2" × 4" × 12' |
| 300 2" × 10" × 12' |
| 3 492 2" × 10" × 12' |
| 132 2" × 8" × 16' |
| 4 216 2" × 8" × 16' |
| 100 2" × 10" × 12' |
| 600 2" × 8" × 8' |
| ______________________________________ |
| TABLE 13 |
| __________________________________________________________________________ |
| Treating Data for CCA/Hydrazine |
| Plant Trial |
| Initial |
| Fill Final Work Tank |
| Solution |
| Charge Wood |
| Vac. Vac. Pressure |
| Empty |
| Vac. Level Retention |
| No. Solution |
| Cu. Ft. |
| Min. |
| "Hg |
| Min. |
| "Hg |
| min. |
| psig |
| min. |
| min. |
| "Hg |
| Start |
| End |
| Gal. |
| pcf |
| __________________________________________________________________________ |
| 1 CCA 838 4 12 6 12 8 150 |
| 9 60 27 30.64 |
| 28.62 |
| 1309.0 |
| 13.12 |
| N2H4 NA NA 19 14 80 55 |
| NA 90 27 21.11 |
| 19.87 |
| 803.5 |
| 8.00 |
| 10 120 |
| 2 CCA 705 NA NA 7 14 6 150 |
| 10 63 28 30.62 |
| 29.12 |
| 972.0 |
| 11.58 |
| N2H4 5 12 27 12 10 91 |
| 23 45 28 20.41 |
| 19.81 |
| 388.8 |
| 4.60 |
| 3 CCA 658 6 14 6 14 10 150 |
| 11 60 28 30.60 |
| 28.87 |
| 1121.0 |
| 14.31 |
| N2H4 3 12 16 12 5 57 |
| 26 NA 28 20.00 |
| 19.75 |
| 162.0 |
| 2.05 |
| 4 CCA 741 3 13 5 13 10 150 |
| 12 60 27 30.61 |
| 28.78 |
| 1185.8 |
| 13.44 |
| N2H4 2 12 20 12 NA 20 |
| 19 NA 27 19.75 |
| 19.62 |
| 84.2 |
| 0.95 |
| __________________________________________________________________________ |
| TABLE 14 |
| ______________________________________ |
| Treating Cycle and Data for |
| Chemical Fixation via Hydroxylamine |
| ______________________________________ |
| CCA Hydroxylamine |
| ______________________________________ |
| Initial Vacuum, inches Hg |
| 10 27 |
| Initial Vacuum, minutes |
| 5 4 |
| Pressure, psig 150 atmospheric |
| Pressure, minutes 30 30 |
| Pressure Release, min. |
| 7 -- |
| Final Vacuum, inches Hg |
| 27 27 |
| Final Vacuum, minutes |
| 45 30 |
| ______________________________________ |
| Sample Pre Treat Post Treat |
| Soln. Gain |
| No. Wt. (g) Wt. (g) (g) |
| ______________________________________ |
| 1 46.55 66.88 20.33 |
| 2 48.25 68.57 20.32 |
| 3 46.71 66.64 19.93 |
| 4 49.29 69.90 20.61 |
| 5 53.56 78.21 24.65 |
| 6 49.61 70.65 21.04 |
| ______________________________________ |
| TABLE 15 |
| ______________________________________ |
| Treating Cycle for Dual Modified Full |
| Cell Chemical Fixation: Oxalic Acid |
| CCA Oxalic Acid |
| First Cycle |
| Second Cycle |
| ______________________________________ |
| Initial Vacuum, inches Hg |
| 10 27 |
| Initial Vacuum, minutes |
| 5 30 |
| Pressure, psig 150 atmospheric |
| Pressure, minutes |
| 30 60 |
| Final Vacuum, inches Hg |
| 27 27 |
| Final Vacuum, minutes |
| 30* 30 |
| ______________________________________ |
| *The CCA's final vacuum was the oxalic acid's initial vacuum. |
| TABLE 16 |
| ______________________________________ |
| Modified Full Cell (Dual Treatment) |
| 2.00% CCA-C/1.25% Oxalic Acid |
| Treating Data |
| % Oxides |
| Sample |
| Pre Treat Post Treat |
| Soln. Gain |
| Soln. Retention |
| No. Wt. (g) Wt. (g) (g) Gain (pcf) |
| ______________________________________ |
| 1 58.94 88.25 29.31 49.73 0.46 |
| 2 56.37 81.89 25.52 45.27 0.40 |
| 3 56.25 81.28 25.03 44.50 0.39 |
| 4 56.06 69.24 13.18 23.51 0.20 |
| 5 35.78 58.67 22.89 63.97 0.36 |
| 6 54.36 78.67 23.83 43.45 0.37 |
| 7 50.78 74.88 24.10 47.46 0.37 |
| 8 58.48 85.31 26.83 45.88 0.42 |
| 9 60.45 88.78 28.33 46.87 0.44 |
| 10 55.43 80.67 25.24 45.53 0.39 |
| 11 55.32 79.75 24.43 44.16 0.38 |
| 12 59.92 90.07 30.15 50.32 0.47 |
| ______________________________________ |
| TABLE 17 |
| ______________________________________ |
| CCA Fixation:Chemical Fixation via Oxalic |
| Acid (1.25%) |
| Time Percent |
| Days Fixation |
| ______________________________________ |
| 0.12 96 |
| 0.23 99+ |
| ______________________________________ |
It will be appreciated that there has been described a method for effectively fixing CCA treating agents in wood. Although the invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made as an example and that the scope of the invention is defined by what is hereafter claimed.
Pasek, Eugene A., Brayman, Theron R., Wall, Gregory D.
| Patent | Priority | Assignee | Title |
| 10449691, | Dec 23 2015 | American Chemet Corporation | Methods for enhancing the preservation of cellulosic materials and cellulosic materials prepared thereby |
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| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Jun 21 1988 | Hickson Corporation | (assignment on the face of the patent) | / | |||
| Jun 24 1988 | PASEK, EUGENE A | KOPPERS COMPANY, INC | ASSIGNMENT OF ASSIGNORS INTEREST | 005094 | /0447 | |
| Jun 24 1988 | WALL, GREGORY D | KOPPERS COMPANY, INC | ASSIGNMENT OF ASSIGNORS INTEREST | 005094 | /0447 | |
| Jul 06 1988 | BRAYMAN, THERON R | KOPPERS COMPANY, INC | ASSIGNMENT OF ASSIGNORS INTEREST | 005094 | /0447 | |
| Apr 26 1989 | KOPPERS COMPANY, INC | BEAZER MATERIALS AND SERVICES, INC | CHANGE OF NAME SEE DOCUMENT FOR DETAILS JANUARY 26,1989 DELAWARE | 005106 | /0052 |
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